1. Field of the Invention
The present invention relates to a substrate treatment apparatus for supplying a treatment solution to a substrate such as a semiconductor wafer, an LCD glass substrate and so on and treating it.
2. Description of the Related Art
Generally, in the photolithography technique in manufacturing process of a semiconductor device, a series of processes is performed such that a resist solution that is a coating solution is applied to the front surface of a substrate, such as a semiconductor wafer (hereinafter, referred to as a wafer), a resist film formed by the application of the solution is exposed to light according to a predetermined circuit pattern, and the exposed pattern is subjected to developing treatment to form a desired circuit pattern in the resist film.
In a resist coating unit and a developing treatment unit, a spinner system is employed in which a treatment solution such as a resist solution, a developing solution, or the like is supplied (discharged, dripped) to the wafer surface and the wafer is rotated, whereby a treatment solution film is formed on the wafer surface and treated. In this event, air is exhausted from the lower portion of a treatment container for housing the wafer.
However, a problem with, in particular, a large-sized wafer (for example, a wafer having a size larger than 300 mm) is that the treatment at an appropriate rotation cannot be performed and that exhaust of air cannot be uniformly performed due to an increase in size of the treatment container to cause mist occurring during treatment to attach to the wafer again.
In addition, in the resist coating, an appropriate rotation of the wafer increases the circumferential speed at the outer peripheral portion of the wafer accompanying the high speed ration, with the result that a region where the film thickness is disturbed to decrease the quality of the film appears at a boundary between a laminar flow region flowing in a radial direction of the wafer at a low speed rotation and a turbulent flow region flowing in the circumferential direction of the wafer at a high speed rotation. More specifically, Ekman spiral vortices occur in the flow in the circumferential direction in the boundary region between the laminar flow and the turbulent flow and disturb the film thickness to decrease the film quality.
Conventionally, an annular ring portion opened on the wafer side is provided on the inner periphery of the treatment container, and a multiblade centrifugal fan having many radial fins along a direction from the rotation direction of the wafer to the outer side is disposed on the annular ring portion to prevent reattachment of the mist to the wafer (see claims and FIG. 1 in Japanese Patent Application Laid-open No. H4-303919).
However, a problem in the above-described conventional technique is that treatment cannot be performed at an appropriate number of rotations of the wafer, failing to solve the decrease the film quality due to the disturbance of the film thickness.